Orion Transporter 70 Min-EQ 9859 Instruction Manual page 6

Big Dipper
(in Ursa Major)
Figure 5.
To find Polaris in the night sky, look north and find the Big Dipper. Extend an imaginary line from the two "Pointer Stars" in the
bowl of the Big Dipper. Go about five times the distance between those stars and you'll reach Polaris, which lies within 1° of the north
celestial pole (NCP).
time. That apparent motion is caused by the Earth's rotation
(from west to east). An equatorial mount (Figure 4) is designed
to compensate for that motion, allowing you to easily "track"
the movement of astronomical objects, thereby keeping them
from drifting out of the telescope's field of view while you're
observing.
This is accomplished by slowly rotating the telescope on its right
ascension (R.A.) axis, using only the R.A. slow-motion cable.
But first the R.A. axis of the mount must be aligned with the
Earth's rotational (polar) axis – a process called polar align-
ment.
Polar alignment
For Northern hemisphere observers, approximate polar align-
ment is achieved by pointing the mount's R.A. axis at the North
Star, or Polaris. It lies within 1° of the north celestial pole
(NCP), which is an extension of the Earth's rotational axis out
into space. Stars in the Northern hemisphere appear to
revolve around the NCP.
To find Polaris in the sky, look north and locate the pattern of
the Big Dipper (Figure 5). The two stars at the end of the "bowl"
of the Big Dipper point right to Polaris.
Observers in the Southern hemisphere aren't so fortunate to
have a bright star so near the south celestial pole (SCP). The
star Sigma Octantis lies about 1° from the SCP, but it is barely
visible with the naked eye (magnitude 5.5).
To polar-align the Transporter 70 Min-EQ:
1. Place the telescope on a flat, level surface, such as a stur-
dy table.
6
Little Dipper
(in Ursa Minor)
N.C.P.
Polaris
2. Loosen the latitude lock T-bolt. Turn the latitude adjustment
T-bolt and tilt the mount until the pointer on the latitude
scale is set at the latitude of your observing site. If you
don't know your latitude, consult a geographical atlas to
find it. For example, if your latitude is 35° North, set the
pointer to 35. Then retighten the latitude lock T-bolt. The
latitude setting should not have to be adjusted again unless
you move to a different viewing location some distance
away.
3. Loosen the Dec. lock knob and rotate the telescope optical
tube until it is parallel with the R.A. axis, as it is in Figure 1.
The pointer on the Dec. setting circle should read 90°.
Retighten the Dec. lock lever.
4. Loosen the azimuth lock knob at the base of the equatorial
mount and rotate the mount so the telescope tube (and
R.A. axis) points roughly at Polaris. If you cannot see
Polaris directly from your observing site, consult a com-
pass and rotate the mount so the telescope points North.
Retighten the azimuth lock knob.
The equatorial mount is now polar aligned.
From this point on in your observing session, you should not
make any further adjustments in the azimuth or the latitude of
the mount, nor should you move the tripod. Doing so will undo
the polar alignment. The telescope should be moved only
about its R.A. and Dec. axes.
use of the r.a. and Dec. slow-Motion control
cables
The R.A. and Dec. slow-motion control cables allow fine
adjustment of the telescope's position to center objects within
Cassiopeia